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  • C# Check for missing number in sequence

    - by Jon
    I have an List<int> which contains 1,2,4,7,9 for example. I have a range from 0 to 10. Is there a way to determine what numbers are missing in that sequence? I thought LINQ might provide an option but I can't see one In the real world my List could contain 100,000 items so performance is key

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  • Loading the last related record instantly for multiple parent records using Entity framework

    - by Guillaume Schuermans
    Does anyone know a good approach using Entity Framework for the problem described below? I am trying for our next release to come up with a performant way to show the placed orders for the logged on customer. Of course paging is always a good technique to use when a lot of data is available I would like to see an answer without any paging techniques. Here's the story: a customer places an order which gets an orderstatus = PENDING. Depending on some strategy we move that order up the chain in order to get it APPROVED. Every change of status is logged so we can see a trace for statusses and maybe even an extra line of comment per status which can provide some extra valuable information to whoever sees this order in an interface. So an Order is linked to a Customer. One order can have multiple orderstatusses stored in OrderStatusHistory. In my testscenario I am using a customer which has 100+ Orders each with about 5 records in the OrderStatusHistory-table. I would for now like to see all orders in one page not using paging where for each Order I show the last relevant Status and the extra comment (if there is any for this last status; both fields coming from OrderStatusHistory; the record with the highest Id for the given OrderId). There are multiple scenarios I have tried, but I would like to see any potential other solutions or comments on the things I have already tried. Trying to do Include() when getting Orders but this still results in multiple queries launched on the database. Each order triggers an extra query to the database to get all orderstatusses in the history table. So all statusses are queried here instead of just returning the last relevant one, plus 100 extra queries are launched for 100 orders. You can imagine the problem when there are 100000+ orders in the database. Having 2 computed columns on the database: LastStatus, LastStatusInformation and a regular Linq-Query which gets those columns which are available through the Entity-model. The problem with this approach is the fact that those computed columns are determined using a scalar function which can not be changed without removing the formula from the computed column, etc... In the end I am very familiar with SQL and Stored procedures, but since the rest of the data-layer uses Entity Framework I would like to stick to it as long as possible, even though I have my doubts about performance. Using the SQL approach I would write something like this: WITH cte (RN, OrderId, [Status], Information) AS ( SELECT ROW_NUMBER() OVER (PARTITION BY OrderId ORDER BY Id DESC), OrderId, [Status], Information FROM OrderStatus ) SELECT o.Id, cte.[Status], cte.Information AS StatusInformation, o.* FROM [Order] o INNER JOIN cte ON o.Id = cte.OrderId AND cte.RN = 1 WHERE CustomerId = @CustomerId ORDER BY 1 DESC; which returns all orders for the customer with the statusinformation provided by the Common Table Expression. Does anyone know a good approach using Entity Framework?

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  • Does table columns increase select statement execution time

    - by paokg4
    I have 2 tables, same structure, same rows, same data but the first has more columns (fields). For example: I select the same 3 fields from both of them (SELECT a,b,c FROM mytable1 and then SELECT a,b,c FROM mytable2) I've tried to run those queries on 100,000 records (for each table) but at the end I got the same execution time (0.0006 sec) Do you know if the number of the columns (and in the end the size of the one table is bigger than the other) has to do something with the query execution time?

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  • Samba with remote LDAP authentication doesn`t see users properly

    - by LucasBr
    I'm trying to setup a samba server authenticated by a remote LDAP server, and I'm having some problems that I can't figure how to solve. I was able to make an getent passwd at samba server and I could see all users at ldapserver, but when I tried to access \\SAMBASERVER at my windows box I had this at the /var/log/samba/log.mywindowsbox: <...snip...> [2012/10/19 13:05:22.449684, 2] smbd/sesssetup.c:1413(setup_new_vc_session) setup_new_vc_session: New VC == 0, if NT4.x compatible we would close all old resources. [2012/10/19 13:05:22.449692, 3] smbd/sesssetup.c:1212(reply_sesssetup_and_X_spnego) Doing spnego session setup [2012/10/19 13:05:22.449701, 3] smbd/sesssetup.c:1254(reply_sesssetup_and_X_spnego) NativeOS=[] NativeLanMan=[] PrimaryDomain=[] [2012/10/19 13:05:22.449717, 3] libsmb/ntlmssp.c:747(ntlmssp_server_auth) Got user=[lucas] domain=[BUSINESS] workstation=[MYWINDOWSBOX] len1=24 len2=24 [2012/10/19 13:05:22.449747, 3] auth/auth.c:216(check_ntlm_password) check_ntlm_password: Checking password for unmapped user [BUSINESS]\[lucas]@[MYWINDOWSBOX] with the new password interface [2012/10/19 13:05:22.449759, 3] auth/auth.c:219(check_ntlm_password) check_ntlm_password: mapped user is: [SAMBASERVER]\[lucas]@[MYWINDOWSBOX] [2012/10/19 13:05:22.449773, 3] smbd/sec_ctx.c:210(push_sec_ctx) push_sec_ctx(0, 0) : sec_ctx_stack_ndx = 1 [2012/10/19 13:05:22.449783, 3] smbd/uid.c:429(push_conn_ctx) push_conn_ctx(0) : conn_ctx_stack_ndx = 0 [2012/10/19 13:05:22.449791, 3] smbd/sec_ctx.c:310(set_sec_ctx) setting sec ctx (0, 0) - sec_ctx_stack_ndx = 1 [2012/10/19 13:05:22.449922, 2] lib/smbldap.c:950(smbldap_open_connection) smbldap_open_connection: connection opened [2012/10/19 13:05:23.001517, 3] lib/smbldap.c:1166(smbldap_connect_system) ldap_connect_system: successful connection to the LDAP server [2012/10/19 13:05:23.007713, 3] smbd/sec_ctx.c:418(pop_sec_ctx) pop_sec_ctx (0, 0) - sec_ctx_stack_ndx = 0 [2012/10/19 13:05:23.007733, 3] auth/auth_sam.c:399(check_sam_security) check_sam_security: Couldn't find user 'lucas' in passdb. [2012/10/19 13:05:23.007743, 2] auth/auth.c:314(check_ntlm_password) check_ntlm_password: Authentication for user [lucas] -> [lucas] FAILED with error NT_STATUS_NO_SUCH_USER [2012/10/19 13:05:23.007760, 3] smbd/error.c:80(error_packet_set) error packet at smbd/sesssetup.c(111) cmd=115 (SMBsesssetupX) NT_STATUS_LOGON_FAILURE [2012/10/19 13:05:23.010469, 3] smbd/process.c:1489(process_smb) Transaction 3 of length 142 (0 toread) <...snip...> /etc/samba/smb.conf file follows: [global] dos charset = 850 unix charset = LOCALE workgroup = BUSINESS netbios name = SAMBASERVER bind interfaces only = true interfaces = lo eth0 eth1 smb ports = 139 hosts deny = All hosts allow = 192.168.78. 192.168.255. 127.0.0.1 10.149.122. 192.168.0. name resolve order = wins bcast hosts log level = 3 syslog = 0 log file = /var/log/samba/log.%m max log size = 100000 domain logons = No wins support = Yes wins proxy = No client ntlmv2 auth = Yes lanman auth = Yes ntlm auth = Yes dns proxy = Yes time server = Yes security = user encrypt passwords = Yes obey pam restrictions = Yes ldap password sync = Yes unix password sync = Yes passdb backend = ldapsam:"ldap://192.168.78.206" ldap ssl = off ldap admin dn = uid=root,ou=Users,dc=business,dc=intranet ldap suffix = ldap group suffix = ou=Groups ldap user suffix = ou=Users ldap machine suffix = ou=Computers ldap idmap suffix = ou=Idmap ldap delete dn = Yes add user script = /usr/sbin/smbldap-useradd -m "%u" delete user script = /usr/sbin/smbldap-userdel "%u" add group script = /usr/sbin/smbldap-groupadd -p "%g" delete group script = /usr/sbin/smbldap-groupdel "%g" add user to group script = /usr/sbin/smbldap-groupmod -m "%u" "%g" delete user from group script = /usr/sbin/smbldap-groupmod -x "%u" "%g" set primary group script = /usr/sbin/smbldap-usermod -g "%g" "%u" add machine script = /usr/sbin/smbldap-useradd -W -t5 "%u" idmap backend = ldap:"ldap://192.168.78.206" idmap uid = 16777216-33554431 idmap gid = 16777216-33554431 load printers = No printcap name = /dev/null map acl inherit = Yes map untrusted to domain = Yes enable privileges = Yes veto files = /lost+found/ /publicftp/ So, \\SAMBASERVER says he couldn't find my user, but I can see it by getent passwd . What I can do in order to SAMBASERVER see and authenticate my user? Thanks in advance!

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  • "Can't create table" when having to many partitions

    - by Chris
    I am currently having a problem I dont understand. Wherever I look it says mySQL (5.5) / InnoDB doesnt have a table limit. I wanted to test the InnoDB compression and was about to create an empty copy of an existing table and ran into the following problem. this one works: CREATE TABLE `hsc` ( LOTS OF STUFF ) ENGINE=InnoDB CHARSET=utf8 PARTITION BY RANGE (pid) SUBPARTITION BY HASH (cons) SUBPARTITIONS 2 (PARTITION hsc_p0 VALUES LESS THAN (10000) , PARTITION hsc_p1 VALUES LESS THAN (20000) , PARTITION hsc_p2 VALUES LESS THAN (30000) , PARTITION hsc_p3 VALUES LESS THAN (40000) , PARTITION hsc_p4 VALUES LESS THAN (50000) , PARTITION hsc_p40 VALUES LESS THAN (4000000) ); this one doesn't: CREATE TABLE `hsc` ( LOTS OF STUFF ) ENGINE=InnoDB CHARSET=utf8 PARTITION BY RANGE (pid) SUBPARTITION BY HASH (cons) SUBPARTITIONS 2 (PARTITION hsc_p0 VALUES LESS THAN (10000) , PARTITION hsc_p1 VALUES LESS THAN (20000) , PARTITION hsc_p2 VALUES LESS THAN (30000) , PARTITION hsc_p3 VALUES LESS THAN (40000) , PARTITION hsc_p4 VALUES LESS THAN (50000) , PARTITION hsc_p5 VALUES LESS THAN (75000) , PARTITION hsc_p6 VALUES LESS THAN (100000) , PARTITION hsc_p7 VALUES LESS THAN (125000) , PARTITION hsc_p8 VALUES LESS THAN (150000) , PARTITION hsc_p9 VALUES LESS THAN (175000) , PARTITION hsc_p40 VALUES LESS THAN (4000000) ); ERROR 1005 (HY000): Can't create table 'hsc' (errno: 1) Its reproducable by removing the number of partitions and adding them again. it does not have to do anything with the name of the table as i tried various names. there is also enough empty space on the HDD. /dev/simfs 230G 26G 192G 12% /var/lib/mysql.mnt There should be no limit on the partitions http://dev.mysql.com/doc/refman/5.5/en/partitioning-limitations.html Maximum number of partitions. The maximum possible number of partitions for a given table (that does not use the NDB storage engine) is 1024. This number includes subpartitions. i have increased both open_files show variables where variable_name LIKE '%open_files%'; +-------------------+-------+ | Variable_name | Value | +-------------------+-------+ | innodb_open_files | 512 | | open_files_limit | 1536 | +-------------------+-------+ No change. Any clues where should I start looking? UPDATE: the whole thing is running in an openvz environment. i saw in users_beancounters that the numflock was a problem, so i increased it. but the problem still persists. maybe this helps: ulimit -a core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 515011 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 10240 cpu time (seconds, -t) unlimited max user processes (-u) 515011 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited cat /proc/user_beancounters Version: 2.5 uid resource held maxheld barrier limit failcnt 200: kmemsize 9309653 13357056 14372700 14790164 0 lockedpages 0 1008 2048 2048 0 privvmpages 675424 686528 1048576 1572864 0 shmpages 33 673 21504 21504 0 dummy 0 0 9223372036854775807 9223372036854775807 0 numproc 49 90 240 240 0 physpages 243761 246945 0 9223372036854775807 0 vmguarpages 0 0 1048576 1048576 0 oomguarpages 81672 83305 1048576 1048576 0 numtcpsock 6 8 360 360 0 numflock 175 188 512 512 8 numpty 1 9 16 16 0 numsiginfo 0 48 256 256 0 tcpsndbuf 104640 263912 1720320 2703360 0 tcprcvbuf 98304 131072 1720320 2703360 0 othersockbuf 32368 89304 1126080 2097152 0 dgramrcvbuf 0 2312 262144 262144 0 numothersock 19 28 360 360 0 dcachesize 2285052 3624426 3409920 3624960 0 numfile 616 870 9312 9312 0 dummy 0 0 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 numiptent 24 24 128 128 0

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  • Trying to prevent Windows from hibernating/sleeping automatically

    - by user328821
    My Dell XPS 8700 (Win 7) suddenly began putting itself to sleep at 6pm daily, even if I'm typing. I don't know what caused this to occur, except possibly a windows update that took place in the middle of the night. I initially went into settings for power and saw 2 plans set up, one from Dell and the other window's Power saver plan. I set both to never for sleep and hibernate yet it still occurred. I have current drivers and a fairly new UPS that has software to set to shutdown only after power loss. Dell is of little help, can anyone point me in the right direction? I did do the powerdfg -energy program and came up with this: Power Efficiency Diagnostics Report Scan Time 2014-05-08T19:21:48Z Scan Duration 60 seconds System Manufacturer Dell Inc. System Product Name XPS 8700 BIOS Date 08/23/2013 BIOS Version A04 OS Build 7601 Platform Role PlatformRoleDesktop Plugged In true Process Count 115 Thread Count 1631 Report GUID {097caf99-039b-44c3-b154-d797bfbfdfcc} Analysis Results Errors Power Policy:Sleep timeout is disabled (Plugged In) The computer is not configured to automatically sleep after a period of inactivity. System Availability Requests:System Required Request The device or driver has made a request to prevent the system from automatically entering sleep. Requesting Driver Instance HDAUDIO\FUNC_01&VEN_10EC&DEV_0899&SUBSYS_102805B7&REV_1000\4&220b1bbc&0&0001 Requesting Driver Device Realtek High Definition Audio CPU Utilization:Processor utilization is high The average processor utilization during the trace was high. The system will consume less power when the average processor utilization is very low. Review processor utilization for individual processes to determine which applications and services contribute the most to total processor utilization. Average Utilization (%) 9.48 Warnings Platform Timer Resolution:Platform Timer Resolution The default platform timer resolution is 15.6ms (15625000ns) and should be used whenever the system is idle. If the timer resolution is increased, processor power management technologies may not be effective. The timer resolution may be increased due to multimedia playback or graphical animations. Current Timer Resolution (100ns units) 10000 Maximum Timer Period (100ns units) 156001 Platform Timer Resolution:Outstanding Kernel Timer Request A kernel component or device driver has requested a timer resolution smaller than the platform maximum timer resolution. Requested Period 10000 Request Count 2 Platform Timer Resolution:Outstanding Timer Request A program or service has requested a timer resolution smaller than the platform maximum timer resolution. Requested Period 10000 Requesting Process ID 8672 Requesting Process Path \Device\HarddiskVolume3\Program Files (x86)\Mozilla Firefox\firefox.exe Platform Timer Resolution:Outstanding Timer Request A program or service has requested a timer resolution smaller than the platform maximum timer resolution. Requested Period 100000 Requesting Process ID 1212 Requesting Process Path \Device\HarddiskVolume3\Windows\System32\svchost.exe Power Policy:802.11 Radio Power Policy is Maximum Performance (Plugged In) The current power policy for 802.11-compatible wireless network adapters is not configured to use low-power modes. CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace. Process Name audiodg.exe PID 1304 Average Utilization (%) 4.73 Module Average Module Utilization (%) \Device\HarddiskVolume3\Windows\System32\msvcrt.dll 1.88 \Device\HarddiskVolume3\Windows\System32\MaxxAudioAPO5064.dll 1.77 \Device\HarddiskVolume3\Windows\System32\AudioEng.dll 0.80 CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace. Process Name thunderbird.exe PID 6036 Average Utilization (%) 0.35 Module Average Module Utilization (%) \Device\HarddiskVolume3\Program Files (x86)\Mozilla Thunderbird\xul.dll 0.16 \Device\HarddiskVolume3\Program Files (x86)\Mozilla Thunderbird\mozjs.dll 0.05 \SystemRoot\System32\win32k.sys 0.03 CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace. Process Name dwm.exe PID 1340 Average Utilization (%) 0.25 Module Average Module Utilization (%) \Device\HarddiskVolume3\Windows\System32\dwmcore.dll 0.08 \Device\HarddiskVolume3\Windows\System32\nvwgf2umx.dll 0.05 \SystemRoot\system32\ntoskrnl.exe 0.03 CPU Utilization:Individual process with significant processor utilization. This process is responsible for a significant portion of the total processor utilization recorded during the trace.

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  • Can't configure frame relay T1 on Cisco 1760

    - by sonar
    For the past few days I've been trying to configure a data T1 via a Frame Relay. Now I've been pretty unsuccessful at it, and it's been a while, since I've done this so please bare with me. The ISP provided me the following information: 1. IP address 2. Gateway address 3. Encapsulation Frame Relay 4. DLCI 100 5. BZ8 ESF (I think the bz8 was supposed to be b8zs) 6. Time Slot (1 al 24). And what I have configured up until now is the following: interface Serial0/0 ip address <ip address> 255.255.255.252 encapsulation frame-relay service-module t1 timeslots 1-24 frame-relay interface-dlci 100 sh service-module s0/0 (outputs): Module type is T1/fractional Hardware revision is 0.128, Software revision is 0.2, Image checksum is 0x73D70058, Protocol revision is 0.1 Receiver has no alarms. Framing is **ESF**, Line Code is **B8ZS**, Current clock source is line, Fraction has **24 timeslots** (64 Kbits/sec each), Net bandwidth is 1536 Kbits/sec. Last module self-test (done at startup): Passed Last clearing of alarm counters 00:17:17 loss of signal : 0, loss of frame : 0, AIS alarm : 0, Remote alarm : 2, last occurred 00:10:10 Module access errors : 0, Total Data (last 1 15 minute intervals): 0 Line Code Violations, 0 Path Code Violations 0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins 0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs Data in current interval (138 seconds elapsed): 0 Line Code Violations, 0 Path Code Violations 0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins 0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail Secs sh int: FastEthernet0/0 is up, line protocol is up Hardware is PQUICC_FEC, address is 000d.6516.e5aa (bia 000d.6516.e5aa) Internet address is 10.0.0.1/24 MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full-duplex, 100Mb/s, 100BaseTX/FX ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:20:00, output 00:00:00, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog 0 input packets with dribble condition detected 191 packets output, 20676 bytes, 0 underruns 0 output errors, 0 collisions, 1 interface resets 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier 0 output buffer failures, 0 output buffers swapped out Serial0/0 is up, line protocol is down Hardware is PQUICC with Fractional T1 CSU/DSU MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY, loopback not set Keepalive set (10 sec) LMI enq sent 157, LMI stat recvd 0, LMI upd recvd 0, DTE LMI down LMI enq recvd 23, LMI stat sent 0, LMI upd sent 0 LMI DLCI 1023 LMI type is CISCO frame relay DTE FR SVC disabled, LAPF state down Broadcast queue 0/64, broadcasts sent/dropped 2/0, interface broadcasts 0 Last input 00:24:51, output 00:00:05, output hang never Last clearing of "show interface" counters 00:27:20 Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: weighted fair Output queue: 0/1000/64/0 (size/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Reserved Conversations 0/0 (allocated/max allocated) Available Bandwidth 1152 kilobits/sec 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 23 packets input, 302 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 1725 input errors, 595 CRC, 1099 frame, 0 overrun, 0 ignored, 30 abort 246 packets output, 3974 bytes, 0 underruns 0 output errors, 0 collisions, 48 interface resets 0 output buffer failures, 0 output buffers swapped out 4 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up Serial0/0.1 is down, line protocol is down Hardware is PQUICC with Fractional T1 CSU/DSU MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY Last clearing of "show interface" counters never Serial0/0.100 is down, line protocol is down Hardware is PQUICC with Fractional T1 CSU/DSU Internet address is <ip address>/30 MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation FRAME-RELAY Last clearing of "show interface" counters never And everything seems to be accounted for to me, but apparently I'm missing something. My issue is that I'm stuck on interface up, line protocol down, so the T1 doesn't go up. Any ideas? Thank you,

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  • Routes on a sphere surface - Find geodesic?

    - by CaNNaDaRk
    I'm working with some friends on a browser based game where people can move on a 2D map. It's been almost 7 years and still people play this game so we are thinking of a way to give them something new. Since then the game map was a limited plane and people could move from (0, 0) to (MAX_X, MAX_Y) in quantized X and Y increments (just imagine it as a big chessboard). We believe it's time to give it another dimension so, just a couple of weeks ago, we began to wonder how the game could look with other mappings: Unlimited plane with continous movement: this could be a step forward but still i'm not convinced. Toroidal World (continous or quantized movement): sincerely I worked with torus before but this time I want something more... Spherical world with continous movement: this would be great! What we want Users browsers are given a list of coordinates like (latitude, longitude) for each object on the spherical surface map; browsers must then show this in user's screen rendering them inside a web element (canvas maybe? this is not a problem). When people click on the plane we convert the (mouseX, mouseY) to (lat, lng) and send it to the server which has to compute a route between current user's position to the clicked point. What we have We began writing a Java library with many useful maths to work with Rotation Matrices, Quaternions, Euler Angles, Translations, etc. We put it all together and created a program that generates sphere points, renders them and show them to the user inside a JPanel. We managed to catch clicks and translate them to spherical coords and to provide some other useful features like view rotation, scale, translation etc. What we have now is like a little (very little indeed) engine that simulates client and server interaction. Client side shows points on the screen and catches other interactions, server side renders the view and does other calculus like interpolating the route between current position and clicked point. Where is the problem? Obviously we want to have the shortest path to interpolate between the two route points. We use quaternions to interpolate between two points on the surface of the sphere and this seemed to work fine until i noticed that we weren't getting the shortest path on the sphere surface: We though the problem was that the route is calculated as the sum of two rotations about X and Y axis. So we changed the way we calculate the destination quaternion: We get the third angle (the first is latitude, the second is longitude, the third is the rotation about the vector which points toward our current position) which we called orientation. Now that we have the "orientation" angle we rotate Z axis and then use the result vector as the rotation axis for the destination quaternion (you can see the rotation axis in grey): What we got is the correct route (you can see it lays on a great circle), but we get to this ONLY if the starting route point is at latitude, longitude (0, 0) which means the starting vector is (sphereRadius, 0, 0). With the previous version (image 1) we don't get a good result even when startin point is 0, 0, so i think we're moving towards a solution, but the procedure we follow to get this route is a little "strange" maybe? In the following image you get a view of the problem we get when starting point is not (0, 0), as you can see starting point is not the (sphereRadius, 0, 0) vector, and as you can see the destination point (which is correctly drawn!) is not on the route. The magenta point (the one which lays on the route) is the route's ending point rotated about the center of the sphere of (-startLatitude, 0, -startLongitude). This means that if i calculate a rotation matrix and apply it to every point on the route maybe i'll get the real route, but I start to think that there's a better way to do this. Maybe I should try to get the plane through the center of the sphere and the route points, intersect it with the sphere and get the geodesic? But how? Sorry for being way too verbose and maybe for incorrect English but this thing is blowing my mind! EDIT: This code version is related to the first image: public void setRouteStart(double lat, double lng) { EulerAngles tmp = new EulerAngles ( Math.toRadians(lat), 0, -Math.toRadians(lng)); //set route start Quaternion qtStart.setInertialToObject(tmp); //do other stuff like drawing start point... } public void impostaDestinazione(double lat, double lng) { EulerAngles tmp = new AngoliEulero( Math.toRadians(lat), 0, -Math.toRadians(lng)); qtEnd.setInertialToObject(tmp); //do other stuff like drawing dest point... } public V3D interpolate(double totalTime, double t) { double _t = t/totalTime; Quaternion q = Quaternion.Slerp(qtStart, qtEnd, _t); RotationMatrix.inertialQuatToIObject(q); V3D p = matInt.inertialToObject(V3D.Xaxis.scale(sphereRadius)); //other stuff, like drawing point ... return p; } //mostly taken from a book! public static Quaternion Slerp(Quaternion q0, Quaternion q1, double t) { double cosO = q0.dot(q1); double q1w = q1.w; double q1x = q1.x; double q1y = q1.y; double q1z = q1.z; if (cosO < 0.0f) { q1w = -q1w; q1x = -q1x; q1y = -q1y; q1z = -q1z; cosO = -cosO; } double sinO = Math.sqrt(1.0f - cosO*cosO); double O = Math.atan2(sinO, cosO); double oneOverSinO = 1.0f / senoOmega; k0 = Math.sin((1.0f - t) * O) * oneOverSinO; k1 = Math.sin(t * O) * oneOverSinO; // Interpolate return new Quaternion( k0*q0.w + k1*q1w, k0*q0.x + k1*q1x, k0*q0.y + k1*q1y, k0*q0.z + k1*q1z ); } A little dump of what i get (again check image 1): Route info: Sphere radius and center: 200,000, (0.0, 0.0, 0.0) Route start: lat 0,000 °, lng 0,000 ° @v: (200,000, 0,000, 0,000), |v| = 200,000 Route end: lat 30,000 °, lng 30,000 ° @v: (150,000, 86,603, 100,000), |v| = 200,000 Qt dump: (w, x, y, z), rot. angle°, (x, y, z) rot. axis Qt start: (1,000, 0,000, -0,000, 0,000); 0,000 °; (1,000, 0,000, 0,000) Qt end: (0,933, 0,067, -0,250, 0,250); 42,181 °; (0,186, -0,695, 0,695) Route start: lat 30,000 °, lng 10,000 ° @v: (170,574, 30,077, 100,000), |v| = 200,000 Route end: lat 80,000 °, lng -50,000 ° @v: (22,324, -26,604, 196,962), |v| = 200,000 Qt dump: (w, x, y, z), rot. angle°, (x, y, z) rot. axis Qt start: (0,962, 0,023, -0,258, 0,084); 31,586 °; (0,083, -0,947, 0,309) Qt end: (0,694, -0,272, -0,583, -0,324); 92,062 °; (-0,377, -0,809, -0,450)

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  • ASP.NET Web Server Hardware Configuration

    - by Santa Te Banta
    I'm planning on deploying my ASP.NET Web app in the production environment using a Windows Server 2003 machine. But I know nothing about the CPU brand names and what's best. I know 4 GB RAM, with anything over 3 GHz clock speed will be a good bet and will serve a large number of users. But tell me what's the latest and greatest processor brand-names for running a Windows Server 2003 OS today? And what edition of the Windows 2003 Server do I need out of the following, if I have to run a website to support about 100,000 (a hundred thousand) users, 60% of who are expected to be online at all times? Web Edition Standard Enterprise Datacenter source: http://en.wikipedia.org/wiki/Windows_Server_2003 The article says that the Web edition can only support up to 2 GB of RAM. Will that be sufficient for the above user population?

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  • myToys.de GmbH announces integration of ZVT payment terminal interface with Oracle Retail Point-of-Service

    - by user801960
    In our latest guest post, Sascha Kraatz, Developer Oracle E-Business Suite of myToys.de announces the development and integration of its ZVT payment terminal interface with the Oracle Retail Point-of-Service solution. myToys.de GmbH, which runs Oracle Retail Point-of-Service (ORPOS) in its 13 retail stores in Germany (see press release), has developed and implemented a Java-based interface for integrating the ZVT payment terminal with ORPOS. Through the combined support of payment service provider, easycash GmbH, and Ingenico GmbH, Germany´s leading payment terminal provider, myToys.de has become the first organisation to create this new automated solution for the Oracle Retail Point-of-Service, which has eliminated input errors that could occur with manual payment terminals and is localised for the German market. Ingo Stober, head of retail business at myToys.de confirms: “With this solution, we can speed up the payment process, reduce manual errors and enhance the customer experience in our stores”. myToys.de GmbH is a member of the Otto Group and one of the leading multichannel retailers for toys and other kids products in Germany. Customers can choose from over 100,000 attractive products, starting with items for expectant mothers or basic baby equipment to items for school children and beyond. In 2006, the first of 13 myToys.de retail branches was opened. If you would like to find out more about this solution, please contact the head of Oracle E-Business Suite Development at myToys.de, Mr. Ralf Schmilewski, or leave a comment below.

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  • Output = MAXDOP 1

    - by Dave Ballantyne
    It is widely know that data modifications on table variables do not support parallelism, Peter Larsson has a good example of that here .  Whilst tracking down a performance issue,  I saw that using the OUTPUT clause also causes parallelism to not be used. By way of example,  first lets create two tables with a simple parent and child (one to one) relationship, and then populate them with 100,000 rows. Drop table ParentDrop table Childgocreate table Parent(id integer identity Primary Key,data1 char(255))Create Table Child(id integer Primary Key)goinsert into Parent(data1)Select top 1000000 NULL from sys.columns a cross join sys.columns b insert into ChildSelect id from Parentgo If we then execute update Parent set data1 =''from Parentjoin Child on Parent.Id = Child.Id where Parent.Id %100 =1 and Child.id %100 =1 We should see an execution plan using parallelism such as   However,  if the OUTPUT clause is now used update Parent set data1 =''output inserted.idfrom Parentjoin Child on Parent.Id = Child.Id where Parent.Id %100 =1 and Child.id %100 =1   The execution plan shows that Parallelism was not used Make of that what you will, but i thought that this was a pretty unexpected outcome. Update : Laurence Hoff has mailed me to note that when the OUTPUT results are captured to a temporary table using the INTO clause,  then parallelism is used.  Naturally if you use a table variable then there is still no parallelism  

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  • Bandwidth Limit User

    - by user45611
    Hello, i'm saxtor i would like to know how to limit users bandwidth for 10gb per day however i dont want to limit them by ipaddress because if they where to go to an internet cafe the users at the cafe will be restricted with that quota, i need to log them via sockets, example the user request to download a file from http://localhost with there username and password, when they download the file sql will update there bandwidth they used, i have a script here but its not working my buffer doesnt work that rate when a user uses multiple connections thanks for the help!. /** * @author saxtor if you can improve this code email me @saxtorinc.com * @copyright 2010 / /* * CREATE TABLE IF NOT EXISTS max_traffic ( id int(255) NOT NULL AUTO_INCREMENT, limit int(255) NOT NULL, PRIMARY KEY (id) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=0 ; */ //SQL Connection [this is hackable for testing] date_default_timezone_set("America/Guyana"); mysql_connect("localhost", "root", "") or die(mysql_error()); mysql_select_db("Quota") or die(mysql_error()); function quota($id) { $result = mysql_query("SELECT `limit` FROM max_traffic WHERE id='$id' ") or die(error_log(mysql_error()));; $row = mysql_fetch_array($result); return $row[0]; } function update_quota($id,$value) { $result = mysql_query("UPDATE `max_traffic` SET `limit`='$value' WHERE id='$id'") or die(mysql_error()); return $value; } if ( quota(1) != 0) $limit = quota(1); else $limit = 0; $multipart = false; //was a part of the file requested? (partial download) $range = $_SERVER["HTTP_RANGE"]; if ($range) { //pass client Range header to rapidshare // _insert($range); $cookie .= "\r\nRange: $range"; $multipart = true; header("X-UR-RANGE-Range: $range"); } $url = 'http://127.0.0.1/puppy.iso'; $filename = basename($url); //octet-stream + attachment = client always stores file header('Content-type: application/octet-stream'); header('Content-Disposition: attachment; filename="'.$filename.'"'); //always included so clients know this script supports resuming header("Accept-Ranges: bytes"); //awful hack to pass rapidshare the premium cookie $user_agent = ini_get("user_agent"); ini_set("user_agent", $user_agent . "\r\nCookie: enc=$cookie"); $httphandle = fopen($url, "r"); $headers = stream_get_meta_data($httphandle); $size = $headers["wrapper_data"][6]; $sizer = explode(' ',$size); $size = $sizer[1]; //let's check the return header of rapidshare for range / length indicators //we'll just pass these to the client foreach ($headers["wrapper_data"] as $header) { $header = trim($header); if (substr(strtolower($header), 0, strlen("content-range")) == "content-range") { // _insert($range); header($header); header("X-RS-RANGE-" . $header); $multipart = true; //content-range indicates partial download } elseif (substr(strtolower($header), 0, strlen("Content-Length")) == "content-length") { // _insert($range); header($header); header("X-RS-CL-" . $header); } } if ($multipart) header('HTTP/1.1 206 Partial Content'); flush(); $speed = 4128; $packet = 1; //this is private dont touch. $bufsize = 128; //this is private dont touch/ $bandwidth = 0; //this is private dont touch. while (!(connection_aborted() || connection_status() == 1) && $size > 0) { while (!feof($httphandle) && $size > 0) { if ($limit <= 0 ) $size = 0; if ( $size < $bufsize && $size != 0 && $limit != 0) { echo fread($httphandle,$size); $bandwidth += $size; } else { if( $limit != 0) echo fread($httphandle,$bufsize); $bandwidth += $bufsize; } $size -= $bufsize; $limit -= $bufsize; flush(); if ($speed > 0 && ($bandwidth > $speed*$packet*103)) { usleep(100000); $packet++; //update_quota(1,$limit); } error_log(update_quota(1,$limit)); $limit = quota(1); //if( $size <= 0 ) // exit; } fclose($httphandle); } exit; ?

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  • What is the definition of "Big Data"?

    - by Ben
    Is there one? All the definitions I can find describe the size, complexity / variety or velocity of the data. Wikipedia's definition is the only one I've found with an actual number Big data sizes are a constantly moving target, as of 2012 ranging from a few dozen terabytes to many petabytes of data in a single data set. However, this seemingly contradicts the MIKE2.0 definition, referenced in the next paragraph, which indicates that "big" data can be small and that 100,000 sensors on an aircraft creating only 3GB of data could be considered big. IBM despite saying that: Big data is more simply than a matter of size. have emphasised size in their definition. O'Reilly has stressed "volume, velocity and variety" as well. Though explained well, and in more depth, the definition seems to be a re-hash of the others - or vice-versa of course. I think that a Computer Weekly article title sums up a number of articles fairly well "What is big data and how can it be used to gain competitive advantage". But ZDNet wins with the following from 2012: “Big Data” is a catch phrase that has been bubbling up from the high performance computing niche of the IT market... If one sits through the presentations from ten suppliers of technology, fifteen or so different definitions are likely to come forward. Each definition, of course, tends to support the need for that supplier’s products and services. Imagine that. Basically "big data" is "big" in some way shape or form. What is "big"? Is it quantifiable at the current time? If "big" is unquantifiable is there a definition that does not rely solely on generalities?

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  • C#/.NET &ndash; Finding an Item&rsquo;s Index in IEnumerable&lt;T&gt;

    - by James Michael Hare
    Sorry for the long blogging hiatus.  First it was, of course, the holidays hustle and bustle, then my brother and his wife gave birth to their son, so I’ve been away from my blogging for two weeks. Background: Finding an item’s index in List<T> is easy… Many times in our day to day programming activities, we want to find the index of an item in a collection.  Now, if we have a List<T> and we’re looking for the item itself this is trivial: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // can find the exact item using IndexOf() 5: var pos = list.IndexOf(64); This will return the position of the item if it’s found, or –1 if not.  It’s easy to see how this works for primitive types where equality is well defined.  For complex types, however, it will attempt to compare them using EqualityComparer<T>.Default which, in a nutshell, relies on the object’s Equals() method. So what if we want to search for a condition instead of equality?  That’s also easy in a List<T> with the FindIndex() method: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // finds index of first even number or -1 if not found. 5: var pos = list.FindIndex(i => i % 2 == 0);   Problem: Finding an item’s index in IEnumerable<T> is not so easy... This is all well and good for lists, but what if we want to do the same thing for IEnumerable<T>?  A collection of IEnumerable<T> has no indexing, so there’s no direct method to find an item’s index.  LINQ, as powerful as it is, gives us many tools to get us this information, but not in one step.  As with almost any problem involving collections, there are several ways to accomplish the same goal.  And once again as with almost any problem involving collections, the choice of the solution somewhat depends on the situation. So let’s look at a few possible alternatives.  I’m going to express each of these as extension methods for simplicity and consistency. Solution: The TakeWhile() and Count() combo One of the things you can do is to perform a TakeWhile() on the list as long as your find condition is not true, and then do a Count() of the items it took.  The only downside to this method is that if the item is not in the list, the index will be the full Count() of items, and not –1.  So if you don’t know the size of the list beforehand, this can be confusing. 1: // a collection of extra extension methods off IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item in the collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // note if item not found, result is length and not -1! 8: return list.TakeWhile(i => !finder(i)).Count(); 9: } 10: } Personally, I don’t like switching the paradigm of not found away from –1, so this is one of my least favorites.  Solution: Select with index Many people don’t realize that there is an alternative form of the LINQ Select() method that will provide you an index of the item being selected: 1: list.Select( (item,index) => do something here with the item and/or index... ) This can come in handy, but must be treated with care.  This is because the index provided is only as pertains to the result of previous operations (if any).  For example: 1: // assume have a list of ints: 2: var list = new List<int> { 1, 13, 42, 64, 121, 77, 5, 99, 132 }; 3:  4: // you'd hope this would give you the indexes of the even numbers 5: // which would be 2, 3, 8, but in reality it gives you 0, 1, 2 6: list.Where(item => item % 2 == 0).Select((item,index) => index); The reason the example gives you the collection { 0, 1, 2 } is because the where clause passes over any items that are odd, and therefore only the even items are given to the select and only they are given indexes. Conversely, we can’t select the index and then test the item in a Where() clause, because then the Where() clause would be operating on the index and not the item! So, what we have to do is to select the item and index and put them together in an anonymous type.  It looks ugly, but it works: 1: // extensions defined on IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // finds an item in a collection, similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: // if you don't name the anonymous properties they are the variable names 8: return list.Select((item, index) => new { item, index }) 9: .Where(p => finder(p.item)) 10: .Select(p => p.index + 1) 11: .FirstOrDefault() - 1; 12: } 13: }     So let’s look at this, because i know it’s convoluted: First Select() joins the items and their indexes into an anonymous type. Where() filters that list to only the ones matching the predicate. Second Select() picks the index of the matches and adds 1 – this is to distinguish between not found and first item. FirstOrDefault() returns the first item found from the previous clauses or default (zero) if not found. Subtract one so that not found (zero) will be –1, and first item (one) will be zero. The bad thing is, this is ugly as hell and creates anonymous objects for each item tested until it finds the match.  This concerns me a bit but we’ll defer judgment until compare the relative performances below. Solution: Convert ToList() and use FindIndex() This solution is easy enough.  We know any IEnumerable<T> can be converted to List<T> using the LINQ extension method ToList(), so we can easily convert the collection to a list and then just use the FindIndex() method baked into List<T>. 1: // a collection of extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // find the index of an item in the collection similar to List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: return list.ToList().FindIndex(finder); 8: } 9: } This solution is simplicity itself!  It is very concise and elegant and you need not worry about anyone misinterpreting what it’s trying to do (as opposed to the more convoluted LINQ methods above). But the main thing I’m concerned about here is the performance hit to allocate the List<T> in the ToList() call, but once again we’ll explore that in a second. Solution: Roll your own FindIndex() for IEnumerable<T> Of course, you can always roll your own FindIndex() method for IEnumerable<T>.  It would be a very simple for loop which scans for the item and counts as it goes.  There’s many ways to do this, but one such way might look like: 1: // extension methods for IEnumerable<T> 2: public static class EnumerableExtensions 3: { 4: // Finds an item matching a predicate in the enumeration, much like List<T>.FindIndex() 5: public static int FindIndex<T>(this IEnumerable<T> list, Predicate<T> finder) 6: { 7: int index = 0; 8: foreach (var item in list) 9: { 10: if (finder(item)) 11: { 12: return index; 13: } 14:  15: index++; 16: } 17:  18: return -1; 19: } 20: } Well, it’s not quite simplicity, and those less familiar with LINQ may prefer it since it doesn’t include all of the lambdas and behind the scenes iterators that come with deferred execution.  But does having this long, blown out method really gain us much in performance? Comparison of Proposed Solutions So we’ve now seen four solutions, let’s analyze their collective performance.  I took each of the four methods described above and run them over 100,000 iterations of lists of size 10, 100, 1000, and 10000 and here’s the performance results.  Then I looked for targets at the begining of the list (best case), middle of the list (the average case) and not in the list (worst case as must scan all of the list). Each of the times below is the average time in milliseconds for one execution as computer over the 100,000 iterations: Searches Matching First Item (Best Case)   10 100 1000 10000 TakeWhile 0.0003 0.0003 0.0003 0.0003 Select 0.0005 0.0005 0.0005 0.0005 ToList 0.0002 0.0003 0.0013 0.0121 Manual 0.0001 0.0001 0.0001 0.0001   Searches Matching Middle Item (Average Case)   10 100 1000 10000 TakeWhile 0.0004 0.0020 0.0191 0.1889 Select 0.0008 0.0042 0.0387 0.3802 ToList 0.0002 0.0007 0.0057 0.0562 Manual 0.0002 0.0013 0.0129 0.1255   Searches Where Not Found (Worst Case)   10 100 1000 10000 TakeWhile 0.0006 0.0039 0.0381 0.3770 Select 0.0012 0.0081 0.0758 0.7583 ToList 0.0002 0.0012 0.0100 0.0996 Manual 0.0003 0.0026 0.0253 0.2514   Notice something interesting here, you’d think the “roll your own” loop would be the most efficient, but it only wins when the item is first (or very close to it) regardless of list size.  In almost all other cases though and in particular the average case and worst case, the ToList()/FindIndex() combo wins for performance, even though it is creating some temporary memory to hold the List<T>.  If you examine the algorithm, the reason why is most likely because once it’s in a ToList() form, internally FindIndex() scans the internal array which is much more efficient to iterate over.  Thus, it takes a one time performance hit (not including any GC impact) to create the List<T> but after that the performance is much better. Summary If you’re concerned about too many throw-away objects, you can always roll your own FindIndex() method, but for sheer simplicity and overall performance, using the ToList()/FindIndex() combo performs best on nearly all list sizes in the average and worst cases.    Technorati Tags: C#,.NET,Litte Wonders,BlackRabbitCoder,Software,LINQ,List

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  • Perl script and out of memory errors

    - by Kevin
    We have a midsized server with 48GB of RAM and are attempting to import a list of around 100,000 opt-in email subscribers to a new list management system written in Perl. From my understanding, Perl doesn't have imposed memory limits like PHP, and yet we are continuously getting internal server errors when attempting to do the import. When investigating the error logs, we see that the script ran out of memory. Since perl doesn't have a setting to limit the memory usage (as far as I can tell) why are we getting these errors? I doubt a small import like this is consuming 48GB of ram. We have compromised and split the list into chunks of 10,000, but would like to figure out the root cause for future fixes. This is a CentOS machine with Litespeed as the web server.

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  • A tale from a Stalker

    - by Peter Larsson
    Today I thought I should write something about a stalker I've got. Don't get me wrong, I have way more fans than stalkers, but this stalker is particular persistent towards me. It all started when I wrote about Relational Division with Sets late last year(http://weblogs.sqlteam.com/peterl/archive/2010/07/02/Proper-Relational-Division-With-Sets.aspx) and no matter what he tried, he didn't get a better performing query than me. But this I didn't click until later into this conversation. He must have saved himself for 9 months before posting to me again. Well... Some days ago I get an email from someone I thought i didn't know. Here is his first email Hi, I want a proper solution for achievement the result. The solution must be standard query, means no using as any native code like TOP clause, also the query should run in SQL Server 2000 (no CTE use). We have a table with consecutive keys (nbr) that is not exact sequence. We need bringing all values related with nearest key in the current key row. See the DDL: CREATE TABLE Nums(nbr INTEGER NOT NULL PRIMARY KEY, val INTEGER NOT NULL); INSERT INTO Nums(nbr, val) VALUES (1, 0),(5, 7),(9, 4); See the Result: pre_nbr     pre_val     nbr         val         nxt_nbr     nxt_val ----------- ----------- ----------- ----------- ----------- ----------- NULL        NULL        1           0           5           7 1           0           5           7           9           4 5           7           9           4           NULL        NULL The goal is suggesting most elegant solution. I would like see your best solution first, after that I will send my best (if not same with yours)   Notice there is no name, no please or nothing polite asking for my help. So, on the top of my head I sent him two solutions, following the rule "Work on SQL Server 2000 and only standard non-native code".     -- Peso 1 SELECT               pre_nbr,                              (                                                           SELECT               x.val                                                           FROM                dbo.Nums AS x                                                           WHERE              x.nbr = d.pre_nbr                              ) AS pre_val,                              d.nbr,                              d.val,                              d.nxt_nbr,                              (                                                           SELECT               x.val                                                           FROM                dbo.Nums AS x                                                           WHERE              x.nbr = d.nxt_nbr                              ) AS nxt_val FROM                (                                                           SELECT               (                                                                                                                     SELECT               MAX(x.nbr) AS nbr                                                                                                                     FROM                dbo.Nums AS x                                                                                                                     WHERE              x.nbr < n.nbr                                                                                        ) AS pre_nbr,                                                                                        n.nbr,                                                                                        n.val,                                                                                        (                                                                                                                     SELECT               MIN(x.nbr) AS nbr                                                                                                                     FROM                dbo.Nums AS x                                                                                                                     WHERE              x.nbr > n.nbr                                                                                        ) AS nxt_nbr                                                           FROM                dbo.Nums AS n                              ) AS d -- Peso 2 CREATE TABLE #Temp                                                         (                                                                                        ID INT IDENTITY(1, 1) PRIMARY KEY,                                                                                        nbr INT,                                                                                        val INT                                                           )   INSERT                                            #Temp                                                           (                                                                                        nbr,                                                                                        val                                                           ) SELECT                                            nbr,                                                           val FROM                                             dbo.Nums ORDER BY         nbr   SELECT                                            pre.nbr AS pre_nbr,                                                           pre.val AS pre_val,                                                           t.nbr,                                                           t.val,                                                           nxt.nbr AS nxt_nbr,                                                           nxt.val AS nxt_val FROM                                             #Temp AS pre RIGHT JOIN      #Temp AS t ON t.ID = pre.ID + 1 LEFT JOIN         #Temp AS nxt ON nxt.ID = t.ID + 1   DROP TABLE    #Temp Notice there are no indexes on #Temp table yet. And here is where the conversation derailed. First I got this response back Now my solutions: --My 1st Slt SELECT T2.*, T1.*, T3.*   FROM Nums AS T1        LEFT JOIN Nums AS T2          ON T2.nbr = (SELECT MAX(nbr)                         FROM Nums                        WHERE nbr < T1.nbr)        LEFT JOIN Nums AS T3          ON T3.nbr = (SELECT MIN(nbr)                         FROM Nums                        WHERE nbr > T1.nbr); --My 2nd Slt SELECT MAX(CASE WHEN N1.nbr > N2.nbr THEN N2.nbr ELSE NULL END) AS pre_nbr,        (SELECT val FROM Nums WHERE nbr = MAX(CASE WHEN N1.nbr > N2.nbr THEN N2.nbr ELSE NULL END)) AS pre_val,        N1.nbr AS cur_nbr, N1.val AS cur_val,        MIN(CASE WHEN N1.nbr < N2.nbr THEN N2.nbr ELSE NULL END) AS nxt_nbr,        (SELECT val FROM Nums WHERE nbr = MIN(CASE WHEN N1.nbr < N2.nbr THEN N2.nbr ELSE NULL END)) AS nxt_val   FROM Nums AS N1,        Nums AS N2  GROUP BY N1.nbr, N1.val;   /* My 1st Slt Table 'Nums'. Scan count 7, logical reads 14 My 2nd Slt Table 'Nums'. Scan count 4, logical reads 23 Peso 1 Table 'Nums'. Scan count 9, logical reads 28 Peso 2 Table '#Temp'. Scan count 0, logical reads 7 Table 'Nums'. Scan count 1, logical reads 2 Table '#Temp'. Scan count 3, logical reads 16 */  To this, I emailed him back asking for a scalability test What if you try with a Nums table with 100,000 rows? His response to that started to get nasty.  I have to say Peso 2 is not acceptable. As I said before the solution must be standard, ORDER BY is not part of standard SELECT. Try this without ORDER BY:  Truncate Table Nums INSERT INTO Nums (nbr, val) VALUES (1, 0),(9,4), (5, 7)  So now we have new rules. No ORDER BY because it's not standard SQL! Of course I asked him  Why do you have that idea? ORDER BY is not standard? To this, his replies went stranger and stranger Standard Select = Set-based (no any cursor) It’s free to know, just refer to Advanced SQL Programming by Celko or mail to him if you accept comments from him. What the stalker probably doesn't know, is that I and Mr Celko occasionally are involved in some conversation and thus we exchange emails. I don't know if this reference to Mr Celko was made to intimidate me either. So I answered him, still polite, this What do you mean? The SELECT itself has a ”cursor under the hood”. Now the stalker gets rude  But however I mean the solution must no containing any order by, top... No problem, I do not like Peso 2, it’s very non-intelligent and elementary. Yes, Peso 2 is elementary but most performing queries are... And now is the time where I started to feel the stalker really wanted to achieve something else, so I wrote to him So what is your goal? Have a query that performs well, or a query that is super-portable? My Peso 2 outperforms any of your code with a factor of 100 when using more than 100,000 rows. While I awaited his answer, I posted him this query Ok, here is another one -- Peso 3 SELECT             MAX(CASE WHEN d = 1 THEN nbr ELSE NULL END) AS pre_nbr,                    MAX(CASE WHEN d = 1 THEN val ELSE NULL END) AS pre_val,                    MAX(CASE WHEN d = 0 THEN nbr ELSE NULL END) AS nbr,                    MAX(CASE WHEN d = 0 THEN val ELSE NULL END) AS val,                    MAX(CASE WHEN d = -1 THEN nbr ELSE NULL END) AS nxt_nbr,                    MAX(CASE WHEN d = -1 THEN val ELSE NULL END) AS nxt_val FROM               (                              SELECT    nbr,                                        val,                                        ROW_NUMBER() OVER (ORDER BY nbr) AS SeqID                              FROM      dbo.Nums                    ) AS s CROSS JOIN         (                              VALUES    (-1),                                        (0),                                        (1)                    ) AS x(d) GROUP BY           SeqID + x.d HAVING             COUNT(*) > 1 And here is the stats Table 'Nums'. Scan count 1, logical reads 2, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0. It beats the hell out of your queries…. Now I finally got a response from my stalker and now I also clicked who he was. This is his reponse Why you post my original method with a bit change under you name? I do not like it. See: http://www.sqlservercentral.com/Forums/Topic468501-362-14.aspx ;WITH C AS ( SELECT seq_nbr, k,        DENSE_RANK() OVER(ORDER BY seq_nbr ASC) + k AS grp_fct   FROM [Sample]         CROSS JOIN         (VALUES (-1), (0), (1)         ) AS D(k) ) SELECT MIN(seq_nbr) AS pre_value,        MAX(CASE WHEN k = 0 THEN seq_nbr END) AS current_value,        MAX(seq_nbr) AS next_value   FROM C GROUP BY grp_fct HAVING min(seq_nbr) < max(seq_nbr); These posts: Posted Tuesday, April 12, 2011 10:04 AM Posted Tuesday, April 12, 2011 1:22 PM Why post a solution where will not work in SQL Server 2000? Wait a minute! His own solution is using both a CTE and a ranking function so his query will not work on SQL Server 2000! Bummer... The reference to "Me not like" are my exact words in a previous topic on SQLTeam.com and when I remembered the phrasing, I also knew who he was. See this topic http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=159262 where he writes a query and posts it under my name, as if I wrote it. So I answered him this (less polite). Like I keep track of all topics in the whole world… J So you think you are the only one coming up with this idea? Besides, “M S solution” doesn’t work.   This is the result I get pre_value        current_value                             next_value 1                           1                           5 1                           5                           9 5                           9                           9   And I did nothing like you did here, where you posted a solution which you “thought” I should write http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=159262 So why are you yourself using ranking function when this was not allowed per your original email, and no cte? You use CTE in your link above, which do not work in SQL Server 2000. All this makes no sense to me, other than you are trying your best to once in a lifetime create a better performing query than me? After a few hours I get this email back. I don't fully understand it, but it's probably a language barrier. >>Like I keep track of all topics in the whole world… J So you think you are the only one coming up with this idea?<< You right, but do not think you are the first creator of this.   >>Besides, “M S Solution” doesn’t work. This is the result I get <<   Why you get so unimportant mistake? See this post to correct it: Posted 4/12/2011 8:22:23 PM >> So why are you yourself using ranking function when this was not allowed per your original email, and no cte? You use CTE in your link above, which do not work in SQL Server 2000. <<  Again, why you get some unimportant incompatibility? You offer that solution for current goals not me  >> All this makes no sense to me, other than you are trying your best to once in a lifetime create a better performing query than me? <<  No, I only wanted to know who you will solve it. Now I know you do not have a special solution. No problem. No problem for me either. So I just answered him I am not the first, and you are not the first to come up with this idea. So what is your problem? I am pretty sure other people have come up with the same idea before us. I used this technique all the way back to 2007, see http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=93911 Let's see if he returns...  He did! >> So what is your problem? << Nothing Thanks for all replies; maybe we have some competitions in future, maybe. Also I like you but you do not attend it. Your behavior with me is not friendly. Not any meeting… Regards //Peso

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  • Strategy for managing lots of pictures for a website

    - by Nate
    I'm starting a new website that will (hopefully) have a lot of user generated pictures. I'm trying to figure out the best way to store and serve these pictures. The CMS I'm using (umbraco) has a media library that puts a folder on the server for each image. Inside of there you can have different sizes of that same image. That folder has an ID on it and the database has additional information for that image along with the ID of the folder. This works great for small sites, but what if the pictures get up to 10,000, 100,000 or 1,000,000? It seems like the lookup on the directory would take a long time to find the correct folder. I'm on windows 2008 if that makes a difference. I'm not so worried about load. I can load balance my server pretty easily and replicate the images across the servers. The nature of the site won't have a lot of users on it either, but it could have a lot of pics. Thanks. -Nate EDIT After some thought I think I'm going to create a directory for each user under a root image folder then have user's pictures under that. I would be pretty stoked if I had even 5,000 users, so that shouldn't be too bad of a linear lookup. If it does get slow I will break it down into folders like /media/a/adam/image123.png. If it ever gets really big I will expand the above method to build a bigger tree. That would take a LOT of content though.

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  • How many times can data be read from a USB flash drive?

    - by John
    While I am aware that performing writes on a USB flash drive degrades the life expectancy of the device. I have heard the quantity of writes is anywhere from 100 thousand to 10 million, but I have not heard about number of read operations. Does reading from the device count toward this total? I am interested in writing only once to a flash drive and setting it to read-only. Then reading files from the device a thousand or more times per day, but am wondering if (at say 1,000 reads per day), the flash drive will need to be replaced within 100 days (assuming a 100,000 r/w cycle lifetime)?

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  • Strategy for managing lots of pictures for a website

    - by Nate
    I'm starting a new website that will (hopefully) have a lot of user generated pictures. I'm trying to figure out the best way to store and serve these pictures. The CMS I'm using (umbraco) has a media library that puts a folder on the server for each image. Inside of there you can have different sizes of that same image. That folder has an ID on it and the database has additional information for that image along with the ID of the folder. This works great for small sites, but what if the pictures get up to 10,000, 100,000 or 1,000,000? It seems like the lookup on the directory would take a long time to find the correct folder. I'm on windows 2008 if that makes a difference. I'm not so worried about load. I can load balance my server pretty easily and replicate the images across the servers. The nature of the site won't have a lot of users on it either, but it could have a lot of pics. Thanks. -Nate EDIT After some thought I think I'm going to create a directory for each user under a root image folder then have user's pictures under that. I would be pretty stoked if I had even 5,000 users, so that shouldn't be too bad of a linear lookup. If it does get slow I will break it down into folders like /media/a/adam/image123.png. If it ever gets really big I will expand the above method to build a bigger tree. That would take a LOT of content though.

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  • Deleting MySQL rows causes lock table error

    - by Dave L
    I had a couple million rows to delete but they can't be deleted at once without this error ERROR 1206 (HY000): The total number of locks exceeds the lock table size So I wrote a script to delete 100,000 rows 10,000 at a time. It ran once but when I run it a second time I get the error on the first attempt to delete 10,000. The way I'm trying to delete the 10,000 rows is to use a delete statement that refers to all 2 million rows but I use a limit clause to affect only 10,000. I've tried adding an "unlock tables;" statement to the script before the first delete but that doesn't help. I still get the lock table error on the first delete. Any ideas how I can do this? Is there a way I can tell it NOT to lock records? I can make sure nothing else is accessing the table.

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  • SQL Azure Federation - how much data before performance benefits?

    - by Donald Hughes
    To avoid premature optimization, I don't want to implement SQL Azure's Federation too early. Is there a rule of thumb for how much data a table would need to have before seeing performance benefits from sharding? I know there won't be a precise answer as there are too many variables to consider, especially with much of SQL Azure's resources being hidden/unknown. To put it into several, more concrete examples, would Federation improve performance in any of the below table scenarios: 100,000 rows (~ 200 MB) 1,000,000 rows (~ 2 GB) 10,000,000 rows (~ 20 GB) 100,000,000 rows (~ 200 GB) For the sake of elaboration, we can assume this is the largest table that would be federated, which consists of order details, which is joined to an orders table with a 'customer_id' foreign key, which would be the distribution key. This is a fairly standard multi-tenant, CRUD order entry system, with a typical assortment of reporting needs (customer order totals by day/month/year, etc).

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  • Getting the PC speaker to beep

    - by broiyan
    There has been much written on getting the beep sound from Ubuntu releases over the years. Example: fixing the beep My needs are slightly different in that I do not want to ensure sound card beeps are functioning. Instead, I want PC speaker beeps, the kind produced by the original built-in speaker because I believe they will produce less CPU load. I have confirmed that my computer has the PC speaker by unplugging the external speakers and shutting down Ubuntu. At some point in the shutdown and restart process a beep is heard even though the external speakers have no power. I have tried the following: In /etc/modprobe.d/blacklist.conf, turn these lines into comments: #blacklist snd_pcsp #blacklist pcspkr In .bashrc /usr/bin/xset b on /usr/bin/xset b 100 Enable in the gnome terminal: Edit Profile Prefs General Terminal Bell Ensure no "mute" selections in: System Prefs Sound various tabs (uncheck them all). Select "Enable window and button sounds" in: System Prefs Sound Sound Effects In gconf-editor desktop gnome sound, select the three sound check boxes. In gconf-editor apps metacity general select the audible bell check box. Still I get no PC speaker beeps when I send code 7 to the console via my Java program or use echo -e '\a' on the bash command line. What else should I try? Update Since my goal is to minimize load on the CPU, here is a comparison of elapsed times. Each test is for 100,000 iterations. Each variant was performed three times so three results are presented for each. printwriter.format("%c", 7); // 1.3 seconds, 1.5 seconds, 1.5 seconds Toolkit.getDefaultToolkit().beep(); // 0.8 seconds, 0.3 seconds, 0.5 seconds try { Runtime.getRuntime().exec("beep"); } catch (IOException e) { } // 10.3 seconds, 16.3 seconds, 11.4 seconds These runs were done inside Eclipse so multiply by some value less than 1 for standalone execution. Unfortunately, Toolkit's beep is silent on my computer and so is code 7. The beep utility works but has the most cost.

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  • What are the most commonly used and basic Apache htaccess redirects?

    - by bybe
    This question is here so we can offer users who are looking for information on how to make one or more common or basic redirects in Apache using the htaccess file. All future questions pertaining to finding information that is that is covered by the question should be closed as a duplication of this question. As per this Meta question. Whats the point in this question? The idea while not perfect is catch the most commonly asked questions regarding redirects using the htaccess on the Apache platform either on some type of lamp or a live server. The type of answers should be generally those that you could imagine are used by 100,000’s of sites world-wide and are constantly asked here at Pro Webmasters repeatedly over and over in various forms. A few examples of the type of answers we are looking for: How can I redirect non-www to www? How can I redirect a sub domain to the main domain? How can I redirect a sub folder from domain to a root or a subdomain? How can I redirect an old URL to a new URL? A few examples of the types of answers that we are not looking for: Answers that do not involve a redirect. Any answers relating to NGinx, IIS or any other non-Apache platform. Answers that involve custom and complex string or query removals. Resources for Advanced to Complex Mod_Rewrite Rules: Everything you ever wanted to know about mod rewrite rules but were afraid to ask Please note: that this question is still in construction and may need some refining either by myself or a real moderator of Pro Webmasters, if you have any concerns or questions please use the meta page I made a few days back here.

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  • Organizing a random list of objects in Python.

    - by Saebin
    So I have a list that I want to convert to a list that contains a list for each group of objects. ie ['objA.attr1', 'objC', 'objA.attr55', 'objB.attr4'] would return [['objA.attr1', 'objA.attr55'], ['objC'], ['objB.attr4']] currently this is what I use: givenList = ['a.attr1', 'b', 'a.attr55', 'c.attr4'] trgList = [] objNames = [] for val in givenList: obj = val.split('.')[0] if obj in objNames: id = objNames.index(obj) trgList[id].append(val) else: objNames.append(obj) trgList.append([val]) #print trgList It seems to run a decent speed when the original list has around 100,000 ids... but I am curious if there is a better way to do this. Order of the objects or attributes does not matter. Any ideas?

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